In planetary gear systems, a planet gear or a pinion gear can fail by fatigue fracture through the gear rim or by gear tooth breakage. In cases where a planet gear tooth breaks off from the planet gear, the planetary gear system can experience a catastrophic failure when the broken tooth remnants become enmeshed between planet gears and the sun gear and/or between the planet gears and the ring gear. In other cases, a failure can occur due to spalling fatigue damage or other defects to integral bearing races that induce fatigue failure through the rim of the gear. This failure mode can cause the planet pinion teeth to catastrophically lock up due to interference with the mating teeth sun or ring gear teeth. While a catastrophic failure of a planetary gear system in some applications may be an expensive inconvenience, such a failure in an aircraft propulsion system, such as, but not limited to, the propulsion system of a helicopter, can lead to fatal crashes and/or significant damage to the aircraft.